Neurotechnology, Invasiveness and the Extended Mind

According to a standard view, the physical boundary of the person-the skin-and-skull boundary-matters morally because this boundary delineates between where the person begins and the world ends. On the basis of this view we make a distinction between invasive interventions that penetrate this boundary and non-invasive interventions that do not. The development of neuroprosthetics, however, raises questions about the significance of this boundary and the relationship between person and body. In particular it has been argued by appeal to the Extended Mind thesis that mind and person can extend beyond the body, and hence the skin-and-skull boundary is of questionable significance. In this paper I argue that the Extended Mind thesis is consistent with the ethical relevance of the skin-and-skull barrier. Although it can be argued that cognitive processes and aspect of mind can extend beyond the skin-and-skull boundary as EM claims, it does not follow that the person is also extended beyond this boundary. The moral sense of person is closely related to the notion of person as a subject of experiences and this, in turn, is related to the sensory and somatosensory aspects of the body. The development of neuroprosthetics provides us with reason to see that persons can be variously embodied, but this is consistent with the functional and ethical significance of the skin-and-skull boundary.